I'm guided by my appetite rather than a scale, so can't contribute any quantitative data to this discussion! I don't think I have ever counted calories.
But I definitely eat more while I am on a bike tour. Normally I eat three times per day. I don't usually snack. But while touring, I try to eat hourly -- a banana, an apple, a handful of nuts, a granola bar, etc. On some multi-day tours, I substitute energy drinks for regular eating. I think the drinks are awful, but they seem to keep my energy level up.
My appetite becomes ferocious after a few days of touring, probably because my everyday life is sedentary -- a lot more sedentary than a cycle tour!